A Pirani vacuum gauge has been known as a device for measuring a pressure of a gas. The Pirani vacuum gauge is provided with, for example, a filament (electrical resistor) formed of a fine metal wire, and configured to measure the pressure of a gas based on a quantity of heat loss of the filament which is caused by heat exchange between the filament and the gas. Further, with the recent advancement in a micro-electro mechanical system (MEMS) technology, the miniaturization of the pressure sensor using the principle of the Pirani vacuum gauge has progressed. See, for example, Japanese Patent Laid-Open Publication No. 2008-111778 and Japanese Patent Laid-Open Publication No. 2009-300381.